I ran two-hour workshops for designers in 2010. Fifteen in all, free to attend, with about 50% non-designer attendance.

http://vi.to/workshop

Workshops are a lot of work -- I'd spend 8-16 hours prepping for a two-hour one -- but they're one of the most asked-for types of local events in Austin:

  Presentations by my peers		95	92%
  Panel discussions by my peers		74	72%
  Hands-on workshops			73	71%
  Presentations by companies		60	58%
  "Field trips" to related industries	57	55%
  Happy hours				51	50%
  Social/networking lunches		42	41%
  Panel discussions by companies	42	41%
  Other					 2	 2%

I'm happy to answer questions based on the workshops I held, you can reply to this or email me (contact information in my profile).